1. Field of the Invention
The present invention relates to a photoacoustic measurement apparatus that emits light toward a subject and receives the light to detect photoacoustic waves generated within the subject.
In addition, the present invention relates to an insertion device used in the photoacoustic measurement apparatus.
2. Description of the Related Art
In recent years, a non-invasive measurement method using a photoacoustic effect has been drawing attention. In the measurement method, a photoacoustic wave, which is an elastic wave generated as a result of emission of pulsed light having an appropriate wavelength (for example, a wavelength band of visible light, near-infrared light, or intermediate infrared light) to a subject and absorption of the energy of the pulsed light by an absorbing substance in the subject, is detected to quantitatively measure the concentration of the absorbing substance. The absorbing substance in the subject is, for example, glucose or hemoglobin contained in blood. In addition, a technique of detecting such a photoacoustic wave and generating a photoacoustic image based on the detection signal is called photo acoustic imaging (PAI) or photo acoustic tomography (PAT).
Conventionally, surgery, sample collection, and treatment such as chemical injection have been performed by inserting various insertion needles into a subject that is a living body. For example, JP2011-67565A and JP2008-246097A disclose examples of such an insertion needle. JP2011-67565A and JP2008-246097A also disclose an insertion device configured such that an insertion needle is injected to the distal end side by a biasing force, which is generated by a compression spring or the like, in order to insert the insertion needle into a subject.
In the case of performing various treatments using the above-described insertion needle, it is desirable to be able to check the distal end position of the insertion needle for the safety of the subject. WO2014/109148A discloses a technique that enables checking the distal end position of an insertion needle by applying the photo acoustic imaging. In this technique, a light guide member, such as an optical fiber, is disposed in the insertion needle so as to reach the vicinity of the distal end of the insertion needle, and a light absorber that covers the distal end of the light guide member is disposed, so that light propagated through the light guide member is incident on the light absorber from the distal end of the light guide member. Therefore, in the case of performing various treatments using the insertion needle, the distal end of the light guide member, that is, the distal end of the insertion needle can be checked by making the light incident on the light absorber from the distal end of the light guide member to generate photoacoustic waves from the light absorber, detecting the photoacoustic waves, and displaying a photoacoustic image of the light absorber.
On the other hand, JP1995-54855Y (JP-H07-54855Y) has proposed that, in order to acquire a photoacoustic image of a sample in a sample collection portion of an insertion needle (needle-shaped applicator), an optical fiber is inserted into the insertion needle between the rear end of the insertion needle and the sample collection portion, and light is emitted to the sample from the distal end of the optical fiber exposed in the sample collection portion.